The present invention relates to a control or regulating method for a compounder-type injection molding machine.
Compounders are devices for fabricating plastic articles and include essentially a plasticizing unit, which accommodates a screw and receives compounding materials such as plastic granulates, fiber materials and other compounding materials from one or more metering units. These materials are plasticized and advanced in longitudinal direction of the plasticizing unit to a header, as the screw rotates, for transfer to an injection unit in the form of a piston and cylinder arrangement. The injection unit injects the plasticized and heated plastic material into a mold for producing the finished plastic article.
The plastic granulates or like materials are typically fed via lateral metering devices or feed hoppers to the plasticizing unit continuously or intermittently or in dependence on the filling level of the plasticizing unit. Hereby, it may happen that depending on the operating conditions excessive or insufficient amounts of material are supplied. Moreover, the metered amounts have to be readjusted, each time a new article is intended for production.
It would therefore be desirable and advantageous to provide an improved method of controlling or regulating a compounder-type injection molding machine, to obviate prior art shortcomings and to prevent supply of incorrect amounts of materials, without requiring a readjustment, when different amounts are necessary upon an article change.